Modern residential and commercial irrigation systems include subterranean plastic branch pipes that each feed water to multiple sprinklers. Pressurized water is fed to the branch pipes via solenoid actuated values which are energized by an electronic irrigation controller. The controller executes a watering program including programmed run and cycle times for all of the sprinklers on each of the branch pipes, which are collectively referred to as a station.
The sprinklers that are used in residential and commercial irrigation systems fall into several basic categories. Spray-type sprinklers are used for close-in watering and project a fan-shaped pattern of water which is either full circle or some division thereof, e.g. ninety degrees. Adjustable arc spray nozzles have also been used for many years. Rotor-type sprinklers are used where large area coverage is desired and typically eject from a nozzle a single, relatively robust inclined stream of water as much as sixty feet or more. The nozzle is most often oscillated through an adjustable arc utilizing turbine, gear reduction and reversing mechanisms. Rotor-type sprinklers often have replaceable nozzles to vary the precipitation rate, i.e. gallons per minute (GPM), of the sprinkler. Some rotor-type sprinklers used on golf courses have built-in valves. Rotary stream sprinklers simultaneously eject a plurality of smaller inclined streams of water. They are useful in applications where more coverage is needed than can be provided by a spray-type sprinkler, and usually less than that provided by a large rotor-type sprinkler. They also eject an aesthetically pleasing array of slowly moving water streams. One type of a modern rotary stream sprinkler has a pop-up riser with an inverted frusto-conical distributor head. Water is channeled upwardly through a flow-adjustable aperture and impinges on the underside of the distributor head. The distributor head has spiral grooves that form the rotary streams. A viscous damper or a brake mechanism ensures that the distributor head turns slowly so that the reach of the multiple streams is not unduly reduced. The shape of the aperture can be varied to adjust the pattern of coverage of the rotary streams. Some rotary stream sprinklers utilize a turbine driven gear train reduction that slowly rotates the distributor head.